This invention relates to feed distributors of the kind in which liquids with solids in suspension e.g. a slurry, are fed to devices such as thickeners, settling tanks and clarifiers.
While not restricted to thickeners, the invention has particular application to them.
Typically a thickener is fed from a central well which in small units is basically an annulus. With large diameter thickeners, where the depth does not increase in proportion to diameter, it is not possible to obtain an even feed with a standard feedwell. In order to obviate some of the problems of larger diameter feedwells a so-called "Fitch feedwell" has been introduced. While the latter gives good mixing of the incoming feed in thickeners up to a certain diameter, it is thought that it would not give an even feed in large diameter thickeners due to the fact that the Fitch feedwell could develop silt deposits in some circumferential zones and cause segregation of the feed solids.
The tendency to cause silt deposits is aggravated during startup when the feed is invariably at a lower rate than during eventual use. Also if the feed rate fluctuates, silting problems may arise.
Obviously there is a need for a feed distributor which can ameliorate the silting problem.